TNF and amyotrophic lateral sclerosis: Activation of P2X7 in microglia purified from superoxide dismutase 1 (SOD1)-G93A mouse model of ALS exacerbates pro-inflammatory responses exemplified by the levels of cyclooxygenase-2 (COX-2), mitogen-activated protein kinase (MAPK), NADPH oxidase 2 (NOX2), nuclear factor kappa-B (NF-κB), tumor necrosis factor alpha (TNF-α), with a consequent cytotoxicity towards neurons (D’Ambrosi et al., 2009; Apolloni et al., 2013b; Parisi et al., 2016).